Manufacture of photographic bleaching layers



Patented Aug. 31, 1943 MANUFACTURE OF PHOTOGRAPHI BLEACHING LAYERS AndrPolgar and Charlcs Halmos, Paris, France;

vested in the Alien Property Custodian No Drawing. Application December2, 1939, Serial No. 307,324. In France December 3, 1938 7 Claims.

The present invention has for object improvements in the manufacture ofphotographic bleaching layers, said improvements being adapted-toimprove the quality of said layers and their preserving capacity.

It is known that bleaching layers, in particular those which areprepared with sensitisers the action of which is sufilciently high forthem to be used practically, as for instance certain thiocarbamicderivatives, and more particularly sensitisers which are soluble inwater, such as they are defined in the French patent in the name of theapplicants filed on March 16, 1938, for: Process i or the preparation ofphotographic bleaching layers and suitable sensitisers, can only be keptfor a short time before being exposed to light. At the end of a greateror less period of time, a coloured .residue is formed in the layer whichis no longer sensitive to light and does not become discoloured whenexposed. On the other hand, a reversibility or bleaching after exposure,is'noticed, particularly after wetting the prints with water or withother liquids (fixing liquids, etc.) or if the prints are allowed tostay in the air, or if they are exposed to heat. This recoloration takesplace instantaneously when certain dyestuffs for instance oxazines, areused.

These disadvantages are produced by reactions independent of light, andwhich probably take place between the active derivatives (sensitisers),the dye-stuns and the support. Said reaction appear to be of a nonphoto-chemical nature, indicated for instance by .a relatively highcoeiilcient of temperature. Now, it has been found, according to thepresent invention, that particularly stable bleaching layers areobtained, which are of very good keeping qualities, do not form colouredresidues, are non reversible, in short, present only the requiredphoto-chemical reactions, if, in the layers there are introduced,

or if said layers are treated with, organic compounds answering to thegeneral formulae:

l Ru

i As compounds suitable for the present process, there can be cited, byway of non limiting examples, acyl-amides, carbamides, sulphocarb'amides(except the known sensitisers) amidines,

guanidines, hydrazides, hydrazidines, acylhydroxamines, imi'doethers,various heterocyclic compounds, the formulaof which corresponds to thegeneral formulae indicated, etc., as well as their derivatives and theirsalts.

For the preparation of the aqueous layers,'acid amides are especiallysuitable, in particular those which, by hygroscopicity, retain thedampness necessary for the satisfactory operation of the layer. Verygood results have been obtained with acetamide. The layers thus formedpresented, even in presence of sulphuric acid, a stability exceeding sixmonths, sometimes more and did not present recolorations. In certaincases, the simultaneous use of hygroscopic agents (such for instance asglycerol) is recommended.

By way of non limiting examples, various formulae for the preparationofbleaching layers according to the invention will be given hereinafter.

Example 1.The solution for the bleaching layer; is prepared bydissolving 1 gram of basic dye-stuffs in 2 grams of hydrochloric acidand 100 grams of water containing 2% of gelatine.

15 grams of N-di- 3-oxethyl-N'allyl-sulpho-urea are added and finally 20grams of acetamide.

Example 2.In 100 grams of water are dissolved 6 grams of gelatine, /2gram of Nile blue sulphate, and 5 grams of N bis (-5, A,dioxypropyl)-N-allyl-sulpho-urea, 10 grams of sulphourea and 5 grams ofglycerol are added.

Example 3.A bleaching solution similar to that of Example 1 is prepared,and 15 grams of monochloracetamide and 10 grams of glycerol are added.It is applied on paper and exposed to an arc lamp.

Example 4.In 200 grams of water are dissolved 10 grams of gelatine, 6grams of Capri blue, 4 grams of sulphopyronine G sulphate, 8 grams ofmethoxyresorcin-benzeine chloride. 500 grams 01' a 20% alcoholicsolution 01' diethylallyl-sulpho-urea, 100 grams of N-di-p-oxyethyl-Nallylsulpho-urea and 50 grams of N-B-oxyethyl-N'allyl-sulpho-urea andfinally grams of oxamide are gradually added. 20 grams of this solutionis spreadout on a square meter of baryta paper.

Example 5.Ordinary photographic support paper is acidified with dilutedsulphuric acid and it is coated with 20 grams of the following solution:grams of water, 10 grams of gelatine and 10 grams ofpropionyl-hydrazide. Then a sitized paper for photographicbleaching.

Example 7.-30 grams oi cellulose acetate are dissolved in 200 grams ofacetone. To this solution are added, 50 grams of methyl alcoholcontaining 0.08 gram of brilliant cresyl blue, 0.05

gram of sulphorhodamine and 0.10 gram of thio-- fiuoressceine, and then10 grams of oxalic acid, 12 grains of diethylallyl-sulpho-urea and 10grams of succinimide are added. Finally, the solution is run on atransparent film.

Example 8.--A bleaching solution is prepared with 5 grams of basicdye-stuffs and 300 grams of 2% sulphuric acid, 30 grams of thiosinamineand 50 grams of diethyanolallylsulpho-urea. Finally, 35 grams ofimidazole chlorhydrate are added.

Example 9.-An aqueous solution of crystallized violet sensitised bythiosinamine is spread out on paper. A solution of diacetylimine is thenapplied.

We claim:

1. In a process for manufacturing photographic bleaching layers, thestep consisting in introducing in the compositionoi these layers anorganic compound the constitution of which can be set forth by one ofthe tautomer formulae:

in which X represents an element of the oxygen series selected from agroup consisting of 0, Se, Te, and R1, R2, R3 each represents asaturated monovalent element, radical or group with the exception ofcompounds having a sensitizing power, by choosing the organic compoundsin question among the compounds belonging to the following classes: acylamides, acyl imides, amidines, guanidines, hydrazides, hydrazidines, hy-

, droxamic acids, imido-ethers and carbamides.

sition of these layers an amidine.

5. In a process for manufacturing photographic bleaching layers asdefined in claim 1, the step consisting in introducing in thecomposition of these layers a guanidine.

6. In the process of manufacturing photographic bleaching layers, asdefined in claim 1 in which the organic compound introduced is anacylamide.

7. In the process of manufacturing photographic bleaching layers, asdefined in claim 1 in which the organic compound introduced is anacylimide.

an Potash.

